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  #1  
Old 02-18-2008, 07:00 PM
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drivinfaster drivinfaster is offline
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alignment info (VERY long, but good info)

seems like a lot of alignement issues/questions going around with a lot of crazy notions. i am posting this to try to help everyone understand what an alignment entails, and hopefully assist you all in getting better service.

first, alignment measurements should be taken on all 4 wheels. this would be a 'total' alignment. this requires the use of 4 head units attatched and compensated ("calibrated"), one on each wheel. this is where the measurements for camber and toe are taken. if there are no REAR camber and toe measurements, then you did not get a total alignment. you got a 'centerline" alignment. this type of alignment assumes that the rear wheels are at 0 degrees camber (straight up and down) and 0 degrees toe (pointing straight ahead). not even my 86 firebird had that, and it has no rear adjustments (which would get a 'thrust' alignment, for the guys with other rwd vehicles). so the centerline type is just a waste of money since what is assumes to be correct, can, and will never be, "0" on both camber and toe.

so total alignment is the way to go, on any vehicle. not all vehicles have factory adjustments, but there are aftermarket kits available. most common ones would be in stock at larger shops doing a lot of alignment work. bmw has adjustable suspensions, as well as kits for camber (more for performance, which i won't get into here)

when you get an alignment, be aware that you own one of the very best handling vehicles on the planet. be preppared to pay the most for an alignment. it has very particular criteria for performing an alignment. since each model may vary on the specifics, i cannot go into each one. this is just a general criteria which will vary depending on year and model, and possibly even vin break. as a rule, the gas tank should be full, but no less than 3/4. the vehicle will need to be 'loaded' to replicate luggage and/or passengers in the front and rear seats (z's would be exempt from that particular criteria. like i stated, this is general. but they still need to be loaded)
this can be accomplished by having associates of the repair facility sitting in the vehicle while the alignment is being done, or using large weights, and even sandbags. the easiest, safest method would be weights, but please do not freak out if you happen to see this being done to your car. if it makes you feel safer, use an old bedspread on the surfaces. believe me, i loved the customers that prepped the car this way for me.

once the alignment has been completed, there should be a printout with the before and after reading, as well as the specs. this could be like me trying to read an mri. i see the pretty colors, but have no friggin clue what it means. so here are some measurements and the definitions.

(all numbered measurements are in degrees unless otherwise specified)

camber: the inward (-) or outward (+) tilt of the top of the tire from vertical (0 degrees)

cross camber: the total difference between the camber angles. -0.3 on the left and -0.3 on the right would be 0 degrees cross camber, and the tires would look like this "/ \" leaning into each other at the top, while +0.3 L, -0.3 R would be 0.6 degreees cross camber, and look more like this, "/ /", which could create a pull. rule of thumb, you don't want more than 0.5 variance, optimum would be dead on spec for both the front and rear.

caster: the forward or backward tilt of the imaginary line between the top and bottom of the suspension points. in laymans terms, this is best described at the forward or backward tilt of the strut. this will not wear your tires if it is off. no way no how. it is simply like the forks of a bicycle. what this allows would be two things. directional stability and steering return. steering return is what happens when you let the steering wheel slide back through your hands to center after turning. it is also why mercedes benz tires look like they're going to fall off when they're turned full to the one side or the other. higher caster. that's whay bumpercars steer the way they do. negative caster (look at the casters on the front of a shopping cart, they look like they lean back from center, then spin the cart and see how the wheel spins on a dime. (just don't run over the old lady getting the cans of cat food...)

cross caster: similar to cross camber, 5.1 L, 5.7 R, cross caster of 0.6. this may cause a slight drift to the left on a flat road with steering wheel centered, but not likely with 5 degrees of caster. the higher the caster, the higher cross caster would need to be in order for a substantial 'leading', or drift to occur. severe cross caster can cause a pull, but as i said before, it will not wear the tires.

toe: this is the inward (+) or outward (-) pointing of the front of the tires. since this used to be measured on the tires themselves, new tires were required for the alignment to be accurate. this is not so today. we have the technology to take and adjust the alignment measurements accurately even without tires on the wheels. it just makes the vehicle easier to move of the alignment rack and test drive, that's all....this is what will give you a straight steering wheel when the alignment is done.

total toe: this is the little bugger that will wear the tires out. this is akin to cross camber and cross caster, as the sum of this is where the wear comes into play. to illustrate, if i had a vehicle that had a total toe spec of +0.10 degrees, i could have +0.10L, 0 R, and the steering wheel would be crooked. no tire wear, just a crooked steering wheel. a straight steering wheel would have +0.5 on either side.

thrust ange: the imaginary line the rear toe will take, which is different than the centerline of the vehicle, which would be right down the middle.

the correct order of adjustment would be the rear camber, then rear toe, then front caster (if adjustable), front camber, then front toe.

there are other measurements, such as steering axis inclination and included angle, but these are more for finding bent suspension components. these are not adjustable.

in my opinion, hunter makes the best alignment equipment and have a program that pretty much guarantees a centered steering wheel on many of the programs. that being said, it's like saying since i drive a bmw i am a superior driver. individual skill is the key factor. so be very suspect of any alignment tech that states the vehicle drives straight when the wheel is let go. never ever let go of the steering wheel. just hold it straight on a level road to check the alignment. if there is no evidence of feathering, cupping, or other tire wear (and you don't drive like mario andretti) then your alignment should be in check, but don't overlook tire pressure.

well, i think that just about covers it for the basics. i hope that you find this information helpful in maintaining your vehicles. if anyone has any questions i will be more than happy to try to answer them. please feel free to pm me.

thank you for taking the time to read this post.

drivinfaster
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  #2  
Old 02-18-2008, 07:36 PM
DM3MD DM3MD is offline
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Great post, thanks for the info! Not to throw a curve ball at ya, but where does tire rotation come into play? Will uneven tread wear affect alignment in the future?
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  #3  
Old 02-19-2008, 05:52 PM
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tire rotation is to reduce the amount of "scrub" the tire goes through while you steer the vehicle. that is why heavy cornering will tend to feather the edges on the front edges (or corners) of the tires. by rotating them, you allow the tread to wear more evenly. once severe wear occurs, cupping will be evident (if you can see it, it's too late to do anything but replace them) and there could be noise issues at high speeds. i have heard tires so bad that i thought the vehicle had a bad bearing. not all vehicles have tires that can be rotated. on these, the tires are usually directional tread design. if you happen to run these the opposite way you will not damage or destroy the tire. it will not wear the tire out faster. (anyone remember the aqua tread by goodyear??) drove many vehicles with them going the 'wrong' way. rotating the tires will not affect the alignment. curbs, potholes, and just driving over time will affect the alignment.
hope this helps.

drivinfaster
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  #4  
Old 03-30-2008, 07:02 PM
Crnhskr80 Crnhskr80 is offline
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Thank you.

Hey drivin' faster. Just about to take my snows off and put my regular tires on my 04 330 cic convertible. Your post was very helpful. Thanks!
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  #5  
Old 04-04-2008, 05:18 AM
sillycar sillycar is offline
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I was wondering if it was worth getting my alignment done too. When I had my snow tires, my car handled perfectly. Now with my summer, the inside is worn a bit and there is a slight shimmy only at low speeds like 30 mph.

If I don't replace my worn tires, won't I just negate any alignment work I do?
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  #6  
Old 06-17-2009, 12:16 PM
mcolozzi mcolozzi is offline
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Quote:
Originally Posted by drivinfaster View Post
seems like a lot of alignement issues/questions going around with a lot of crazy notions. i am posting this to try to help everyone understand what an alignment entails, and hopefully assist you all in getting better service.

first, alignment measurements should be taken on all 4 wheels. this would be a 'total' alignment. this requires the use of 4 head units attatched and compensated ("calibrated"), one on each wheel. this is where the measurements for camber and toe are taken. if there are no REAR camber and toe measurements, then you did not get a total alignment. you got a 'centerline" alignment. this type of alignment assumes that the rear wheels are at 0 degrees camber (straight up and down) and 0 degrees toe (pointing straight ahead). not even my 86 firebird had that, and it has no rear adjustments (which would get a 'thrust' alignment, for the guys with other rwd vehicles). so the centerline type is just a waste of money since what is assumes to be correct, can, and will never be, "0" on both camber and toe.

so total alignment is the way to go, on any vehicle. not all vehicles have factory adjustments, but there are aftermarket kits available. most common ones would be in stock at larger shops doing a lot of alignment work. bmw has adjustable suspensions, as well as kits for camber (more for performance, which i won't get into here)

when you get an alignment, be aware that you own one of the very best handling vehicles on the planet. be preppared to pay the most for an alignment. it has very particular criteria for performing an alignment. since each model may vary on the specifics, i cannot go into each one. this is just a general criteria which will vary depending on year and model, and possibly even vin break. as a rule, the gas tank should be full, but no less than 3/4. the vehicle will need to be 'loaded' to replicate luggage and/or passengers in the front and rear seats (z's would be exempt from that particular criteria. like i stated, this is general. but they still need to be loaded)
this can be accomplished by having associates of the repair facility sitting in the vehicle while the alignment is being done, or using large weights, and even sandbags. the easiest, safest method would be weights, but please do not freak out if you happen to see this being done to your car. if it makes you feel safer, use an old bedspread on the surfaces. believe me, i loved the customers that prepped the car this way for me.

once the alignment has been completed, there should be a printout with the before and after reading, as well as the specs. this could be like me trying to read an mri. i see the pretty colors, but have no friggin clue what it means. so here are some measurements and the definitions.

(all numbered measurements are in degrees unless otherwise specified)

camber: the inward (-) or outward (+) tilt of the top of the tire from vertical (0 degrees)

cross camber: the total difference between the camber angles. -0.3 on the left and -0.3 on the right would be 0 degrees cross camber, and the tires would look like this "/ \" leaning into each other at the top, while +0.3 L, -0.3 R would be 0.6 degreees cross camber, and look more like this, "/ /", which could create a pull. rule of thumb, you don't want more than 0.5 variance, optimum would be dead on spec for both the front and rear.

caster: the forward or backward tilt of the imaginary line between the top and bottom of the suspension points. in laymans terms, this is best described at the forward or backward tilt of the strut. this will not wear your tires if it is off. no way no how. it is simply like the forks of a bicycle. what this allows would be two things. directional stability and steering return. steering return is what happens when you let the steering wheel slide back through your hands to center after turning. it is also why mercedes benz tires look like they're going to fall off when they're turned full to the one side or the other. higher caster. that's whay bumpercars steer the way they do. negative caster (look at the casters on the front of a shopping cart, they look like they lean back from center, then spin the cart and see how the wheel spins on a dime. (just don't run over the old lady getting the cans of cat food...)

cross caster: similar to cross camber, 5.1 L, 5.7 R, cross caster of 0.6. this may cause a slight drift to the left on a flat road with steering wheel centered, but not likely with 5 degrees of caster. the higher the caster, the higher cross caster would need to be in order for a substantial 'leading', or drift to occur. severe cross caster can cause a pull, but as i said before, it will not wear the tires.

toe: this is the inward (+) or outward (-) pointing of the front of the tires. since this used to be measured on the tires themselves, new tires were required for the alignment to be accurate. this is not so today. we have the technology to take and adjust the alignment measurements accurately even without tires on the wheels. it just makes the vehicle easier to move of the alignment rack and test drive, that's all....this is what will give you a straight steering wheel when the alignment is done.

total toe: this is the little bugger that will wear the tires out. this is akin to cross camber and cross caster, as the sum of this is where the wear comes into play. to illustrate, if i had a vehicle that had a total toe spec of +0.10 degrees, i could have +0.10L, 0 R, and the steering wheel would be crooked. no tire wear, just a crooked steering wheel. a straight steering wheel would have +0.5 on either side.

thrust ange: the imaginary line the rear toe will take, which is different than the centerline of the vehicle, which would be right down the middle.

the correct order of adjustment would be the rear camber, then rear toe, then front caster (if adjustable), front camber, then front toe.

there are other measurements, such as steering axis inclination and included angle, but these are more for finding bent suspension components. these are not adjustable.

in my opinion, hunter makes the best alignment equipment and have a program that pretty much guarantees a centered steering wheel on many of the programs. that being said, it's like saying since i drive a bmw i am a superior driver. individual skill is the key factor. so be very suspect of any alignment tech that states the vehicle drives straight when the wheel is let go. never ever let go of the steering wheel. just hold it straight on a level road to check the alignment. if there is no evidence of feathering, cupping, or other tire wear (and you don't drive like mario andretti) then your alignment should be in check, but don't overlook tire pressure.

well, i think that just about covers it for the basics. i hope that you find this information helpful in maintaining your vehicles. if anyone has any questions i will be more than happy to try to answer them. please feel free to pm me.

thank you for taking the time to read this post.

drivinfaster
would an alignment issue cause a momentary "pulse" to the steering when the brakes are tapped at low speed?
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  #7  
Old 06-18-2009, 12:06 PM
searich07 searich07 is offline
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I read your very informative posting on Alignment, but must tell you that once you have re-calibrated your alignment on four wheels, you can be a tad too fast and hit a parking lot concrete bumper or street curb which can throw your alignment off.
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  #8  
Old 06-18-2009, 02:06 PM
mickey513 mickey513 is offline
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There Firestones around me have the latest Hunter Alignment machine but their technicains are just the biggest FREAKING retards when it comes to doing a alignment on BMWs or Mercedes.
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  #9  
Old 06-22-2009, 08:09 PM
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drivinfaster drivinfaster is offline
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Quote:
Originally Posted by mcolozzi View Post
would an alignment issue cause a momentary "pulse" to the steering when the brakes are tapped at low speed?
no, suspect warped brake rotors.

df
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  #10  
Old 06-22-2009, 08:11 PM
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drivinfaster drivinfaster is offline
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Quote:
Originally Posted by searich07 View Post
I read your very informative posting on Alignment, but must tell you that once you have re-calibrated your alignment on four wheels, you can be a tad too fast and hit a parking lot concrete bumper or street curb which can throw your alignment off.
true, so you could get it reset, or try another curb to adjust the other side...

j/k, but this is why alignments usually do not have much of a warranty aspect to them.
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Old 01-11-2010, 11:48 PM
omodos omodos is offline
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hi are my alignment settings especially rear camber a recipe for worn tires, and as for the total toe I am in range, but it is not split 50/50 per tires per end
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  #12  
Old 01-12-2010, 08:50 AM
6 Brit 6 Brit is offline
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Quote:
Originally Posted by omodos View Post
hi are my alignment settings especially rear camber a recipe for worn tires, and as for the total toe I am in range, but it is not split 50/50 per tires per end
were you in the car when the alignment was done? perhaps it's uneven to compensate for the lack of your weight being in the car or just because AWD set-ups are funky
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Old 01-12-2010, 08:54 AM
6 Brit 6 Brit is offline
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I have a question Mr. alignment man!

it's been explained to me before but I can't remember all the details for the life of me...

what is different about aligning an AWD vehicle...specifically a truck - ladder frame type?
How is it done? what is different from a regular 2wd unibody alignment? and why the strange set up?
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  #14  
Old 01-13-2010, 06:19 AM
omodos omodos is offline
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Originally Posted by 6 Brit View Post
were you in the car when the alignment was done? perhaps it's uneven to compensate for the lack of your weight being in the car or just because AWD set-ups are funky
Nope was not in the car when it was done, as a matter in fact nobody was in the car, and i read time and time again that car has to be loaded when the alignment is done...99% i drive alone with a tank usually maxed out at half way...well my alignment figures are out, had a few people tell me (thats after gettin the alignment done) so gonna try one last guy and see what he does
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  #15  
Old 01-13-2010, 02:49 PM
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drivinfaster drivinfaster is offline
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brit, there is no difference in the alignment angles for any vehicle. they are all the same. sort of like we have 2 arms and 2 legs.

any 'differences' would be to the specifications of that particular vehicle and the chassis type. it makes no difference whether it is unibody or full frame. the difference is in the intent of the vehicle.

for instance, an awd chassis may be able to go off road in light conditions, there is usually enough ground clearance to do so, but the suspension articulation is not siffucient to do any serious off road stuff.

since very few people use their vehicles in this manner, even the most aggressive factory built 'off road rated' vehicles are still set to an alignment spec that will be more suited for paved roads. this is also true with tires as well.

i hope this clarifies things for ya!!

df
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